Large portions of Maine could feel as warm at 100 degrees on Monday, prompting an official warning about the sticky, sweltering air.

The National Weather Service has issued a heat advisory for most of coastal and interior Maine, urging people to avoid strenuous outdoor activity and drink lots of water. The afternoon heat index is predicted to clock temperatures in the upper 90s, and the air will feel especially oppressive because of the high level of humidity, according to the weather service.

In Greater Bangor on Monday, the high is expected to reach 95 degrees, but it could feel as hot as 102, the forecast predicts.

The combination of heat and humidity will increase a person’s chance of becoming ill because of heat stroke, especially for those with stressed respiratory systems or existing health problems. Drink plenty of water and find cool, air conditioned places to remain throughout the afternoon, the weather service urged.

The advisory will last until 6 p.m. It comes after a string a scorching, sticky days that have been keeping temperatures in Maine in the 80s.

As the sun goes down Monday over Bangor, the heat is predicted to break into windy thunderstorms just before 10 p.m.

The stormy weather is expected throughout the day in the Queen City on Tuesday, when temperatures could reach 92 degrees but feel like 99, according to the weather service.